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Counter: Go Ahead with Non-Contrast CTs Safely Saves Time and Money

Contrast protocols, including intravenous, oral and/or rectal contrast,
are just not necessary for abdominal CTs. From my perspective, the only
emergent CTs that warrant IV contrast administration are CT pulmonary
angiograms to identify pulmonary emboli, chest or abdominal CTs to
investigate suspicion for aortic dissection and perhaps for blunt
abdominal trauma.
Several studies have shown the accuracy of unenhanced or non-contrast
studies. Their accuracy has been proven for almost any intra-abdominal
process you could consider.

Keyzer reported in 2009 that in 131 patients, comparing oral and IV
protocols to IV only, visualization of the appendix was dependant upon
the reader not the protocol (AJR Am J Roentgenol. 2009
Nov;193(5):1272-81.). Beyond the concept of inter-reader variability is
the fact that unenhanced studies are very accurate and are becoming more
so as technology continues to improve. In 1999, Lane reported
unenhanced CTs to be 96% sensitive and 99% specific for appendicitis in
300 consecutive ED patients suspected of having appendicitis (Radiology
213:341, 1999.). In 2002, the British Journal of Radiology reported the
same findings in 108 patients with surgically proven appendicitis. The
sensitivity of unenhanced CTs with 5mm sections was 96% sensitive and
98% specific for appendicitis (Br J Radiol. 2002 Sep;75(897):721-5.).
Some have reported that with less intra-abdominal fat, visualization of
the appendix is more difficult in pediatrics, necessitating contrast to
discern the appendix from other structures. Hoecker, at the Children’s
Hospital of San Diego, reported no difference in the accuracy of
unenhanced CT, compared to findings for enhanced CTs reported by
previous studies. They reported the positive and negative predictive
value to be 91.3% and 90.8%, respectively.

Hill, from Michigan State University, confirmed that for all
non-traumatic intra-abdominal processes, there was no statistical
difference between enhanced and unenhanced studies for making the
correct diagnosis (World J Surg. 2010 Apr;34(4):699-703.), and Tack
reported similar findings for the diagnosis of diverticulitis
(Radiology. 2005 Oct;237(1):189-96.).

Although suggesting a place for IV contrast, the use of oral contrast
provides no benefit for detecting bowel or mesenteric injuries (J
Trauma. 2004 Feb;56(2):314-22.). No evidence refutes the value of IV
contrast for splenic and hepatic vascular injuries, reserving a place
for its use in trauma.

The situation changes if the concern is for an intra-abdominal
vascular catastrophe. Some clinicians mistakenly interchange the terms
aortic dissection, a separation of the intima from the media, and
aneurysm. Although dissections can sometimes be associated with
aneurysms, these two diagnoses are very different. You can have a
leaking or ruptured AAA without a dissection, and you can have a
dissecting aorta without any aneurysmal dilatation. Thus, if you are
looking for a dissection, you need intravenous contrast to show the
false lumen (separation) between the intima and the media. Not so for
aneurysms, as a dilated aorta can be easily seen without contrast. Blood
from a leaking or ruptured AAA is evident without any contrast. The
blood is contrast enough.

The real controversy in the use of oral and/or rectal contrast exists
with abdominal/pelvic studies. Radiologists report the increased
sensitivity of 64 and 128-slice MDCT scanners and warn us constantly of
hypersensitivity reactions, albeit less likely with non-ionic contrast,
and contrast-induced nephrotoxicity. And yet, they still want us to use
contrast to “improve imaging quality.” If they want to limit the risk of
acute hypersensitivity reactions and nephrotoxicity, they need to quit
demanding contrast when the evidence just doesn’t support its use.

In addition to posing additional unnecessary risk to the patient,
using contrast also causes substantial operational issues in every
emergency department, resulting in increased throughput times,
diagnostic delays and less patients being seen. For example, if an oral
contrast protocol takes 90 minutes to complete (delivery, ingestion of
the contrast and waiting for it to traverse the GI tract) and 10 ED
patients undergo this protocol daily, a cascading effect of delays will
result. Those ten protocols will cost your department 15 hours of bed
time. This equates to 5,475 hours annually. If the average length of
stay (all comers) is two hours, 2,737 less patients can be seen in your
department annually, resulting in $273,700 less physician reimbursement
(assuming an average $100 collected per patient) and $1,095,000 less
revenue for the hospital in ED charges alone (assuming an average of
$400 per visit for the facility/hospital side).

So if the contrast is not clinically necessary, per the research, and
it’s obstructing the ED, why are we still doing it? The radiologists
claim they get better results. However, their own literature suggests
that they don’t. To quote Rick Bukata: If we put their own literature in
a Mercedes catalog, maybe they’ll read it. The fact is that whatever
marginal benefit in image quality is perceived by some Radiologists is
most likely personal preference and is so minor that it doesn’t aid them
in getting the right answer.

There are limitations to CT with any abdominal process. However, the
use of contrast doesn’t remedy those concerns. It has been proposed that
we should just order “renal stone protocol CTs” and avoid the argument
altogether. I don’t advocate this approach for two reasons. First,
without disclosing what pathology we are truly looking for, we are
handicapping the Radiologist, impairing their ability to appropriately
interpret the study. If you’re worried about appendicitis, they need to
know that. The second reason is that we shouldn’t hide from this
discussion. If we stop calling this practice into question, I fear it
will be accepted as standard practice, resulting in delays, ED
inefficiency and potential patient complications.